We had our ducklings out today, trying to get them used to being handled, and one of them slipped and hit his head on the table. At first he couldn't stand up straight at all. Now he can stand but he is having trouble walking. He falls all over his own feet while trying to walk. He's eating, drinking and pooping ok and seems ok,otherwise. He is isolated away from the other ducks, just so we can keep an eye on him. Is this something I need to worry about, or will he improve on his own?